Multiple-gate injection molding apparatus

ABSTRACT

One or more nozzles define separate nozzle channels. The nozzles are coupled to a manifold, so that each of the nozzle channels communicates with a different mold gate. A molding material distribution insert is coupled to the manifold and has a body defining a distribution channel and a plurality of drop channels equal in number to the nozzle channels. The distribution channel is an open distribution channel formed on an outer surface of the body and enclosed by the manifold. The drop channels intersect the distribution channel and exit the body at a different one of the nozzle channels. A valve pin bushing can extend into the drop channels. Valve pins can extend from actuators, through the valve pin bushing and the drop channels, and to the mold gates. A valve pin holder can be coupled to the actuator and coupled to heads of the valve pins.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is relates to an injection molding apparatus.

2. Related Art

In injection molding hot runners designed for tight cavity pitch, wherecenter-to-center nozzle channel spacing is on the order of millimeters,distribution of molding material from the mold inlet to the moldcavities is a substantial challenge.

It is typical in the art to use conventional manifold design but providea nozzle in which a single inlet runner branches into a plurality ofoutlet runners. In such systems, tight pitch is achieved by the abilityof the manufacturer to plan and make small-diameter and often skewedchannels. However, this kind of branching design many times results inincreased stack height, which can be undesirable.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the present invention will now be described more fullywith reference to the accompanying drawings, where like referencenumbers indicate similar structure.

FIG. 1 is a cross-sectional view of an injection molding apparatusaccording to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a portion of the injection moldingapparatus of FIG. 1.

FIGS. 3 a and 3 b are perspective views of the molding materialdistribution insert of FIG. 1.

FIG. 4 a is a top view of the molding material distribution insert ofFIG. 1.

FIG. 4 b is a cross-sectional view with respect to a section line A-A ofFIG. 4 a.

FIG. 5 is a perspective view of a molding material distribution insertaccording to another embodiment of the present invention.

FIG. 6 is a perspective view of a molding material distribution insertaccording to another embodiment of the present invention.

FIG. 7 is a side view of a molding material distribution insertaccording to another embodiment of the present invention.

FIG. 8 is a cross-sectional view of an injection molding apparatusaccording to another embodiment of the present invention.

FIG. 9 is a perspective view of the bottom plate of the valve pin holderof FIG. 1 according to an embodiment of the present invention.

FIG. 10 is a perspective view of a molding material distribution insertaccording to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an injection molding apparatus 100 according to anembodiment of the present invention. The features and aspects describedfor the other embodiments can be used accordingly with the presentembodiment.

The injection molding apparatus 100 includes a back plate 102, anactuator 104, a valve pin holder 106, a valve pin bushing 108, amanifold 110, a nozzle 112, valve pins 114, and a molding materialdistribution insert 116. The injection molding apparatus 100 can includeany number of manifolds and nozzles, in any configuration. In thisembodiment, one manifold and one nozzle are shown for simplicity. Theinjection molding apparatus 100 can include additional components, suchas mold plates, alignment dowels, mold gate inserts, and coolingchannels, among others. The injection molding apparatus 100 is sometimescalled a hot runner or hot half.

The back plate 102 has an opening for accommodating the actuator 104 andan opening for the valve pin holder 106 that communicates with theopening for the actuator. The back plate 102 has slots 118 extendinglaterally from the opening for the valve pin holder 106. If the actuator104 depends on a working fluid for operation, fluid conduits 120, 122are provided in the back plate 102. Should the actuator 104 be electricor magnetic or of some other design, the fluid conduits can be replacedwith electrical conduits or can be omitted.

The actuator 104 is disposed in the back plate 102 and can be pneumatic,hydraulic, electric, magnetic, or of some other design. In thisembodiment the actuator 104 is pneumatic. As such, the actuator includesa cylinder 124, a piston 126, a cap plate 128, and various O-rings 130.The piston 126 slides in the cylinder 124 in response to differentialfluid pressure within the fluid conduits 120, 122. The piston 126includes a central bore for receiving a bolt 132 that can be installedand removed via a central opening of the cap plate 128.

The valve pin holder 106 is coupled to the actuator by the bolt 132,which threads into the valve pin holder 106 but not necessarily into thepiston 126 of the actuator 104. The valve pin holder 106 is coupled tothe heads of the valve pins 114 so as to couple the valve pins 114 tothe piston 126. In this embodiment, the valve pin holder 106 includes abottom plate 134 having a plurality of valve pin slots and/or bores anda top member 136 connected to the bottom plate 134 for holding the valvepins 114 in the valve pin slots/bores. As shown, the top member 136 canbe a plate that is bolt-connected to the bottom plate 134. In otherembodiments, the top member 136 can be a threaded cap or similar.

Extending laterally from the valve pin holder 106 are severalanti-rotation dowels 138. Each anti-rotation dowel 138 has one endcoupled to the valve pin holder 106 and another end disposed in one ofthe slots 118 of the back plate 102. By virtue of their dimensions, eachanti-rotation dowel 138 and slot 118 pair are configured to limitrotation of the valve pin holder 106 about a longitudinal axis 140 andallow translation of the valve pin holder 106 along the longitudinalaxis 140. In this embodiment, the anti-rotation dowels 138 are installedinto bores of the top member 136. In other embodiments, a singleanti-rotation dowel can be used.

The valve pin bushing 108 is held to the manifold 110 by the back plate102. The valve pin bushing 108 includes a main body 142 and a pluralityof cylindrical bushing portions 144 connected to and extending from themain body 142. Each bushing portion 144 has a valve pin bore, whichcreates a seal with the valve pin 114 while still allowing the valve pin114 to slide. Like the valve pins 114 in this embodiment, the valve pinbores are parallel. The valve pin bushing 108 further includes onesecuring dowel 146 for each bushing portion 144. Each securing dowel 146has one end connected to a bushing portion 144 and another end connectedto the main body 142 for securing the bushing portion 144 to the mainbody 142. The securing dowels 146 fix the orientation of the bushingportions 144 with respect to the main body 142, so that the angled endsof the bushing portions 144 are properly aligned to guide the flow ofmolding material.

The manifold 110 defines a manifold channel 148, a manifold heater 150,and an opening to accommodate the molding material distribution insert116. The manifold 110 is coupled to the back plate 102 by way of alocating ring and a mold plate and/or other known structures (notshown). The manifold channel 148 receives molding material (e.g.,plastic melt or thermoset material) from a mold inlet (not shown) or anupstream manifold (not shown). The manifold heater 150 can be of anydesign, such as the insulated resistance wire illustrated.

The nozzle 112 is coupled or sealed to the manifold 110 by any means(e.g., flange shouldering, bolts, screw-in, etc.) and defines aplurality of separate nozzle channels 152. In this embodiment there arefour nozzle channels 152 (with two hidden from view), though more orfewer are acceptable. Each of the plurality of nozzle channels 152communicates with a different mold gate 153 (defined by a mold plate ormold gate insert, for example—not shown) and is controlled by adifferent valve pin 114. In addition, in this embodiment the nozzle 112includes a nozzle body 154, a nozzle flange 156, a nozzle heater 158embedded in the nozzle body 154 and partially covered by a sleeve 160, athermocouple 159, a terminal end 162 for connecting the heater 158 to apower source, and nozzle tip and tip retainer assemblies 164. The nozzleflange 156 is shouldered on a mold plate (not shown) to couple/seal thenozzle 112 to the manifold 110. In this embodiment, one nozzle tip andtip retainer assembly 164 is provided for each valve pin 114. In otherembodiments, single-piece tips or other tip/retainer assemblies may beused. The nozzle 112 along with the manifold 110 and optionally some ofthe other components is sometimes called a hot runner. In addition, thenozzle and manifold heaters 150, 158 can be omitted and the injectionmolding apparatus 100 can be used to process cold-runner material.

Cavities 166 to form molded products are provided in communication withthe mold gates 153. In this embodiment, each cavity 166 communicateswith a different mold gate 153, in a one-to-one relationship. In otherembodiments, a cavity could share one or more mold gates. When thecavities 166 are closely spaced, this can be referred to as tight pitch.However, tightly pitched cavities are not the only use for the presentinvention.

The molding material distribution insert 116 is coupled to the manifold110. In this embodiment, the insert 116 is situated inside an opening ofthe manifold 110, much like a plug; however in other embodiments, aportion of the insert 116 could extend outside of the manifold 110. Theinsert 116 includes a cylindrical body 168 defining a distributionchannel 170 in communication with the manifold channel 148 and aplurality of drop channels 172 equal in number to the plurality ofnozzle channels 152. The drop channels 172 intersect the distributionchannel 170 and exit the body 168 at the end adjacent the nozzle 112.Each drop channel 172 communicates with a different nozzle channel 152.

In this embodiment, the distribution channel 170 is an open channelformed on the cylindrical outer surface of the body 168. When the insert116 in inserted into the manifold 110, the distribution channel 170 isenclosed by the manifold 110 and the manifold channel 148 becomes aninlet to the now enclosed distribution channel 170.

The drop channels 172 communicate with the distribution channel 170 andexit the body 168 at the downstream flat end (e.g., ref. 306 of FIG. 3)to convey molding material to the nozzle channels 152. The drop channels172 can be bores, as shown, or can be open channels that are enclosed bythe manifold 110 much like the distribution channel 170. In thisembodiment, the drop channels 172 exit both ends of the body 168. At theupstream end, the bushing portions 144 of the valve pin bushing 108extend into the drop channels 172 so that the valve pins 114 extendthrough the drop channels 172 and to the mold gates 153. In otherembodiments, such as in thermal gating applications where there are novalve pins, the drop channels 172 do not need to exit the upstream endof the body 168 of the insert 116.

Regarding assembly, in this embodiment the molding material distributioninsert 116 is brazed to the manifold 110. In other embodiments, theinsert 116 can soldered, welded, or otherwise thermally/metallurgicallyjoined to the manifold 110. In still other embodiments, the insert 116can be press fitted, shrink fitted, bolted, threaded, or otherwisemechanically joined to the manifold 110. The bolt 132 facilitatesassembly and disassembly of the injection molding apparatus 100 byallowing separation of the back plate 102 and the actuator 104 from therest of the apparatus. When the bolt 132 is being tightened into thevalve pin holder 106, the anti-rotation dowels 138 prevent undue stresson the valve pins 114.

FIG. 2 shows a close-up view of a portion of the injection moldingapparatus of FIG. 1.

FIGS. 3 a and 3 b show perspective views of the molding materialdistribution insert 116. As shown, the annular or ring-shaped opendistribution channel 170 is formed on the cylindrical outer surface 300of the body 168, such that the distribution channel 170 follows acircumferential perimeter of the body 168. In this embodiment, thedistribution channel 170 has two ends 302, 304, such that thedistribution channel 170 does not complete a circle, but rather aportion of a circle.

In this embodiment there are four drop channels 172, marked 172 a-d. Inother embodiments there may be fewer or more drop channels, depending onthe number of nozzle channels 152. The drop channels 172 a-d intersectthe distribution channel 170 and exit the body 168 at the downstreamflat end 306 and at the upstream flat end 308. In this embodiment, thedrop channels 172 a-d are evenly spaced, and one end 302 of thedistribution channel 170 terminates at a first drop channel 172 a whilethe other end 304 of the distribution channel 170 terminates at a dropchannel 172 d adjacent the first drop channel 172 a after havingintersected all of the drop channels 172 a-d. When the insert 116 isinstalled in the manifold 110, the manifold channel 148 meets thedistribution channel 170 between the drop channels 172 b and 172 c.

Also shown in FIGS. 3 a and 3 b is a flange 310 that extends from thebody 168 and aids in securing the insert 116 to the manifold 110. Thecylindrical face of the flange 310 has a bore 312 for receiving analignment dowel (not shown) having a protruding end that is insertedinto a slot of the manifold 110 to properly align the insert 116 withthe manifold channel 148.

Regarding manufacturing, in this embodiment the insert 116 is made froma unitary piece of material, such as steel, that is turned to achievethe cylindrical features. After turning, the distribution channel 170 ismilled and the drop channels 172 are drilled. In another embodiment, theinsert 116 could be cast. In certain circumstances, such as if theinsert 116 is not brazed to the manifold 110, a portion of thecylindrical outer surface 300 can be machined to a sealing tolerance.The same applies to one of the surfaces of the flange 310. If the insert116 is to be bolted to the manifold 110, bolt holes can be drilled intothe flange 310. If the insert is to be threaded into the manifold 110, athread can be machined into one of the cylindrical surfaces, such as thesurface 300 or the cylindrical outside surface of the flange 310, tomate with a corresponding thread machined into the manifold 110.

FIG. 4 a shows a top view of the molding material distribution insert116, and FIG. 4 b shows a cross-sectional view of the insert 116 withrespect to a section line A-A of FIG. 4 a.

Shown in FIG. 4 b is a longitudinal axis 400 of the cylindrical body 168of the insert 116. The circumferential perimeter 402 that thedistribution channel 170 follows is centered about the longitudinal axis400 and defines a circle to which the longitudinal axis 400 is normal.This means that the angle 404 is 90 degrees. Of course, in otherembodiments the angle 404 can have other values resulting in somewhatdifferent geometries. It should be noted that the longitudinal axis 400is not necessarily coincident with the longitudinal axis 140 of FIGS. 1and 2. In this embodiment the axes 400, 140 are the same, but in otherembodiments the axes 400, 140 can be laterally offset and/or at an anglewith respect to each other. Such geometric variations can be taken intoaccount when locating the distribution channel 170 and the drop channels172.

FIG. 5 shows a perspective view of a molding material distributioninsert 500 according to another embodiment of the present invention. Thefeatures and aspects described for the other embodiments can be usedaccordingly with the present embodiment.

The insert 500 includes an inner body piece 502 and a hollow outer bodypiece 504 that is fit around the inner body piece 502. The inner bodypiece 502 and outer body piece 504 can be secured together by way ofbrazing, press fitting, or other methods. A distribution channel 506 isformed as a slot in the outer body piece 504. Drop channels 508 areformed in the inner body piece 502 and intersect with the distributionchannel 506. A flange 510 extends from the outer body piece 504 and hasa bore 512 for receiving an alignment dowel (not shown). The insert 500is an example of one way of making a molding material distributioninsert from two or more pieces, and other ways are possible as well.

FIG. 6 shows a perspective view of a molding material distributioninsert 600 according to another embodiment of the present invention. Thefeatures and aspects described for the other embodiments can be usedaccordingly with the present embodiment.

The insert 600 includes a cylindrical body 602. A distribution channel606 is formed in the body 602 and follows a circular path all the wayaround the body 602 such that the distribution channel 606 circumscribesthe cylindrical body 602. Drop channels 608 are formed in the body 602and intersect with the distribution channel 606. A flange 610 extendsfrom the body 602. The insert 600 can be used in a manifold that has onemanifold channel approaching the distribution channel 606 from one sideand another manifold channel that approaches from the opposite side.

FIG. 7 shows a side view of a molding material distribution insert 700according to another embodiment of the present invention. The featuresand aspects described for the other embodiments can be used accordinglywith the present embodiment.

The insert 700 includes a cylindrical body 702 having a longitudinalaxis 704. An open distribution channel 706 is formed in an outsidesurface of the body 702 and follows a circumferential perimeter 708. Thedistribution channel 706 is tilted when compared with the embodimentshown in FIG. 3, resulting in the circumferential perimeter 708 defininga generally elliptical shape, when viewed along the axis 704, that is ata non-perpendicular angle 710 to the longitudinal axis 704. Dropchannels 712 are formed in the body 702 and intersect with thedistribution channel 706. The tilt of the distribution channel 706 meansthat the drop channels 712 intersect the distribution channel 706 atdifferent points along the longitudinal axis 704. In addition, a flange714 extends from the body 702.

FIG. 8 shows an injection molding apparatus 800 according to anotherembodiment of the present invention. In the description of thisembodiment, like reference numerals in the 800 series are used todescribe parts like those in FIG. 1 for ease of understanding. Onlydiffering features and aspects of the present embodiment are describedin detail. For description of the like parts, the other embodiments canbe referenced. The features and aspects described for the otherembodiments can be used accordingly with the present embodiment.

The injection molding apparatus 800 includes a back plate 802, anactuator 804, a valve pin holder 806, a valve pin bushing 808, amanifold 810, four nozzles 812 (two hidden from view), valve pins 814,and a molding material distribution insert 816. The injection moldingapparatus 800 can include any number of manifolds and nozzles, in anyconfiguration. In this embodiment, one manifold is shown for simplicity.The injection molding apparatus 800 can include additional components,such as mold plates, alignment dowels, mold gate inserts, and coolingchannels, among others. The injection molding apparatus 800 is sometimescalled a hot half.

One main difference between the injection molding apparatus 800 and theapparatus 100 described above is that the injection molding apparatus800 includes four separate nozzles 812, each with its own nozzlechannel. The nozzles 812 are can be coupled to the manifold 810 by anymeans (e.g., flange shouldering, bolts, screw-in, etc.) and each has aseparate nozzle channel that communicates with a different drop channelof the insert 816. In this embodiment, the nozzles 812 have flanges thatare shouldered on a mold plate (not shown). Flow of molding materialthrough each nozzle 812 is controlled by a different valve pin 814. Inaddition, in this embodiment each nozzle 812 includes a nozzle body, anozzle heater, a thermocouple, a terminal end, and a nozzle tip and tipretainer assembly. Of course, in other embodiments, more or fewernozzles could be used, with the design of the other components beingmodified accordingly.

FIG. 9 shows a perspective view of the bottom plate 134 of the valve pinholder 106 according to an embodiment of the present invention.

The bottom plate 134 has a plurality of valve pin slots 902 and aplurality of valve pin bores 904. The valve pin slots 902 and bores 904have T-shaped cross-sections to hold the flattened heads of the valvepins (e.g., ref. 114 of FIG. 1). A center of each valve pin bore 904 isa first distance 906 from a center 908, which need not coincide with thephysical center of the bottom plate 134. Each valve pin slot 902 has alength 910 that is collinear with the center 908. A portion of eachvalve pin slot 902 is the first distance 906 from the center 908. Thisallows for a variety of arrangements of equally-spaced valve pins usingthe same “universal” bottom plate 134. For example, if two valve pinsare used, two opposite valve pin slots 902 are selected, the length ofthe slots 902 giving flexibility in locating the valve pins. The sameapplies for four valve pins, where all four slots 902 are used. If eightvalve pins are needed, all of the slots 902 and the bores 904 arefilled, with the bores 904 limiting the diameter at which the valve pinscan be equally spaced. Of course, other valve pin locations arepossible, and more so when the requirement for equal spacing is relaxed.

To secure the valve pins, a top member (e.g., ref. 136 of in FIG. 1)connects to the bottom plate 134 via bolts (not shown) inserted throughbolt holes 912 for holding valve pins in any of the valve pin slots 902and valve pin bores 904.

In other embodiments, the bottom plate 134 can be larger or smaller andthus can have more or fewer slots and bores.

FIG. 10 shows a cross-sectional view of a molding material distributioninsert 1000 according to another embodiment of the present invention.The features and aspects described for the other embodiments can be usedaccordingly with the present embodiment. The insert 1000 is similar tothe other inserts described herein, and only differences are describedin detail below.

An open distribution channel 1002 is formed on the cylindrical outersurface 1004 of a cylindrical body 1006, such that the distributionchannel 1002 follows a circumferential perimeter of the body 1006. Dropchannels 1008 intersect the distribution channel 1002 and exit the body1006 at a downstream flat end 1010. However, the drop channels 1008 donot exit the body 1006 at the top end and there are no bores for valvepins. As such, the insert 1000 is suitable for thermal gatedapplications.

Although many embodiments of the present invention have been described,those of skill in the art will appreciate that other variations andmodifications may be made without departing from the spirit and scopethereof as defined by the appended claims. All patents and publicationsdiscussed herein are incorporated in their entirety by referencethereto.

What is claimed is:
 1. A molding material distribution insert for a hotrunner, comprising: a cylindrical body having a longitudinal axis; anopen distribution channel formed on a cylindrical outer surface of thebody, the distribution channel following a circumferential perimeter ofthe body; a plurality of drop channels formed in the body andintersecting the distribution channel, wherein the drop channels exitthe body at a first end of the body.
 2. The molding materialdistribution insert of claim 1, wherein the distribution channel has afirst end and a second end.
 3. The molding material distribution insertof claim 2, wherein the plurality of drop channels are evenly spaced,wherein the first end of the distribution channel terminates at a firstdrop channel and the second end of the distribution channel terminatesat a second drop channel adjacent the first drop channel after havingintersected all of the plurality of drop channels.
 4. The moldingmaterial distribution insert of claim 1, wherein the distributionchannel circumscribes the cylindrical body.
 5. The molding materialdistribution insert of claim 1, wherein the circumferential perimeter iscentered about the longitudinal axis.
 6. The molding materialdistribution insert of claim 5, wherein the circumferential perimeterdefines a circle to which the longitudinal axis is normal.
 7. Themolding material distribution insert of claim 1, wherein the dropchannels exit the body at the first end of the body and a second end ofthe body.
 8. The molding material distribution insert of claim 1,wherein an end of the cylindrical body comprises a flange.
 9. Themolding material distribution insert of claim 1, wherein the moldingmaterial distribution insert is a unitary piece.
 10. An injectionmolding apparatus, comprising: a manifold defining a manifold channel;one or more nozzles defining a plurality of separate nozzle channels,the one or more nozzles coupled to the manifold, each of the pluralityof nozzle channels communicating with a different one of a plurality ofmold gates; and a molding material distribution insert coupled to themanifold and comprising a body defining a distribution channel incommunication with the manifold channel and a plurality of drop channelsequal in number to the plurality of nozzle channels, the plurality ofdrop channels intersecting the distribution channel and exiting the bodyat an end of the body, each drop channel in communication with adifferent one of the nozzle channels.
 11. The injection moldingapparatus of claim 10, wherein the distribution channel is an opendistribution channel formed on an outer surface of the body and enclosedby the manifold.
 12. The injection molding apparatus of claim 10,wherein the drop channels exit the body at both ends of the body, theinjection molding apparatus further comprising a plurality of valve pinsextending through the drop channels and to the mold gates.
 13. Theinjection molding apparatus of claim 12 further comprising a valve pinbushing extending into the drop channels.
 14. The injection moldingapparatus of claim 12 further comprising a back plate and an actuatorcoupled to the back plate.
 15. The injection molding apparatus of claim14 further comprising a valve pin holder coupled to the actuator and tothe heads of the valve pins.
 16. The injection molding apparatus ofclaim 15 further comprising at least one anti-rotation dowel having afirst end coupled to the valve pin holder and a second end disposed in aslot of the back plate, wherein the anti-rotation dowel and the slot areconfigured to limit rotation of the valve pin holder about alongitudinal axis and allow translation of the valve pin holder alongthe longitudinal axis.
 17. The injection molding apparatus of claim 15further comprising a bolt coupling a piston of the actuator to the valvepin holder.
 18. The injection molding apparatus of claim 10, wherein themolding material distribution insert is brazed, soldered, or welded tothe manifold.
 19. The injection molding apparatus of claim 10, whereinthe molding material distribution insert is press fit into the manifold.20. An injection molding apparatus, comprising: a back plate; anactuator coupled to the back plate; a manifold coupled to the back plateand defining a manifold channel; one or more nozzles defining aplurality of separate nozzle channels, the one or more nozzles coupledto the manifold, each of the plurality of nozzle channels communicatingwith a different one of a plurality of mold gates; a molding materialdistribution insert coupled to the manifold and comprising a bodydefining a distribution channel in communication with the manifoldchannel and a plurality of drop channels equal in number to theplurality of nozzle channels, wherein the distribution channel is anopen distribution channel formed on an outer surface of the body andenclosed by the manifold, wherein the plurality of drop channelsintersect the distribution channel and exit the body at both ends of thebody, each drop channel in communication with a different one of thenozzle channels; a valve pin bushing extending into the drop channels; aplurality of valve pins extending from the actuator, through the valvepin bushing and the drop channels, and to the mold gates; and a valvepin holder coupled to the actuator and coupled to heads of the valvepins.
 21. A valve pin bushing for a hot runner, comprising: a main body;and a plurality of bushing portions connected to and extending from themain body, each bushing portion having a valve pin bore.
 22. The valvepin bushing of claim 21 further comprising a securing dowel having oneend connected to the main body and another end connected to a bushingportion, the securing dowel for fixing an orientation of a bushingportion with respect to the main body.
 23. An injection moldingapparatus, comprising: an actuator; and a valve pin holder connected tothe actuator, comprising: a bottom plate having a plurality of valve pinslots and a plurality of valve pin bores, wherein each valve pin bore isa first distance from a center, and wherein each valve pin slot has alength that is collinear with the center and a portion of each valve pinslot is the first distance from the center; and a top member connectedto the bottom plate for holding valve pins in any of the valve pin slotsand valve pin bores.